Alien Anthology. It's a better set and personally, I enjoy the Alien films more anyway. This is all a matter of opinion, though.

Better Blu than Red.73 Blus in my collectionLast Watched: The Pacific - Parts 2,3,4 and 5 and The Social NetworkLast Bought/Received: The Social NetworkLast Ordered: The Social NetworkPlayer: Sony PS3 40GBHome Theater: Sony HT-DDWG700

Alien Anthology. Insanely easy choice for me. Aliens was one of my favorite films growing up. I still find Alien terrifying and Alien 3 is enjoyable. While I don't care so much for the 4th I haven't really seen it since it came out and I am willing to give it another chance.

I will still be buying the BttF box set but probably not right when it's released.

You can't really pick between these. Both series are totally opposite of each other and are great for different reasons. There is no easy way to say which one you should get. In the end, it's all going to come down to which genre you like more, an action oriented horror/sci-fi movie, or an action oriented comedy.

"Does the Blu-ray version of '.......' look better than it's DVD version?"

I'm so sick of this question. 99% of Blu-rays look better than their DVD counterpart. Period.